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Sixth Order Extension of the Euclidean Path Integral Method for Taming the Ghost

By root - Posted on 09 junho 2011

Palestrante:

Michele Fontanini, University of Pennsylvania

Data:

Terça-feira, 24 Maio, 2011 - 16:00

Recently there has been an increasing interest in higher derivatives theories, especially in the framework of gravity where they can be used, for instance, to model late time acceleration or inflation. Such models also come quite naturally from higher dimensional braneworld scenarios, where the effect of bulk fields and their symmetries may introduce modifications to the long wavelength behavior of gravity. Unfortunately most higher derivative theories introduce new degrees of freedom, some of which are ghost-like. It is then necessary to find a way to integrate out the infinities related to these extra fields. In particular, it has been proposed that an alternative to the effective field theory approach exists, consisting in an attempt to integrate out the ghosts via the Euclidean path integral formalism. I consider an extension of this idea to systems containing up to six derivatives in the action, showing in principle the consistency of the approach when a Minkowski background is considered, while finding that during inflation corrections due to a particular sixth order term completely spoil the power spectrum.